Colorectal cancer is one of the most prevalent types of lethal cancer worldwide with rising incidence in the younger populations and is associated with poorer prognosis when it affects the liver. Interventional oncology/radiology using thermal ablation techniques (radiofrequency ablation, microwave ablation, cryoablation) has revolutionized the landscape in the treatment of colorectal liver metastases (CLM) achieving comparable results with limited resection in selected cases. In small CLM, minimally invasive, image-guided percutaneous thermal ablation is an effective local curative option. Tumor size, location, and tumor biology are important factors to consider when offering thermal ablation. Moreover, the creation of an ablation zone with at least 5 and ideally 10 mm (A0) minimal ablation margin (MM) is very important. Lastly, three-dimensional software for treatment planning and confirmation of the ablation margin is rapidly evolving and plays an increasingly important role for treatment confirmation and refinement of the oncologic outcomes. This chapter aims to outline the updated evidence regarding the role of thermal ablation in the treatment of CLM. Indications, patient selection, differences in ablation modalities, complications, and factors affecting oncologic outcomes are discussed.